Fluid actuated servo-control device



Jan. 19, 1965 A. AMOUR FLUID ACTUATED sERvo-coNTRoL DEVICE 3 Sheets-Sheet 1 Filed Feb. 5, 1962 INVENTOR.

vl E Jan. 19, 1965 A. AMOUR 3,165,981

FLUID ACTUATED SERVO-CONTROL. DEVICE Filed Feb. 5. 1962 3 Sheets-Sheet 2 y, 3 zo 15 22 5 12 Fig. 4 1e 6 as '.QV

INVENTOR.

Az. Ess/a NDR@ A Mou n ATTORNEY Jan. 19, 1965 A. AMOUR 3,165,981

FLUID ACTUATED SERVO-CONTROL DEVICE Filed Feb. 5, 1962 5 Sheets-Sheet 5 l 'A liv/Illu ll VIII/IH' ss 34 as 311 2s 2? 25 30 a2 si 29 INVENToR. AL Es SANDRO Amun.

BY M dw ATTORNEY i :fates The device according to the invention comprises .a Signp r a w l piston l slidably mounted within a cylinder 2 bored 1n mlm) QTUTED Svl/UN 5E* i a body or casing 3 closed at both its ends by the heads 4 til t u am 1g, 5 passing through the head 4 in a tight manner by means mniwioi idol, of an annular packing 7 and terminating with a portion uw n/51,; ug, 2a 5,951, ggg/ei S, for instance screw-threaded, intended to be connected 6 Claims. (Us. Sd-litt l with the part to be actuated, eg. the engagement lever of a clutch. in the body 3 and in the heads 4, 5, parallel ln modern engineering practice there occur Several 10 to the cylinder 2, there is slidably mounted a cylindrical instances in which a given operation must be aCCOmslide or distributing valve 9, whose end 10 passes through plished with a speed variable in lthe course of said ophead 5 in a tight manner'by virtue of an annular packing eration, according to a predetermined program. For it, and which is for instance screw-threaded for conirlStanCe, in engaging a Clutch trDSmSSiOH device `0r nection with a mechanical, electromagnetic or'like drive the like, the engagement stroke must take place with member. The opposite end of the seat of slide valve 9 `high speed in the first portion, corresponding to -apis closed by means of a plug 12. preach the clutch members, then very slowly in the sec- The body and the heads of the device are formed with ond portion, corresponding to the actual engagement of three connections, one for arrival of a pressure fluid, the saidmembers, and tinally again at high speed in the third other for discharge and the third for regulation, 13, 14 and last portion, corresponding to the application of the and i5 respectively. At the outside of the device, said normal working pressure -to the clutch members already arrival and discharge connections are connected with the engaged, as well as to the accomplishment of `a short idle outlet andthe inlet of a pump P respectively, while the stroke of the drive members. Similar requirements may connection iS is connected to discharge 14 through la iiow have to be ul'lled in the braking of moving parts and regulator member R, consisting of a gauged diaphragm, in many other instances. In still further cases, the drive or a tap with adjustable plunger, or the like. portions to be r.accomplished at diiierent speeds may be The connection` 13 can be put in communication only two in number, -or else they may be more than three. (Ri-i. position of the slide valve) with a pipe i6 indicated in all these instances, the use of servo-control devices with broken lines and opening at i7 in communica-tion involves diliicult problems, which may be solved only by with connection i4, as well as at 18 in a port disposed means of complex devices, adapted to carry out the pro- 3o in a predetermined position in the Wall of cylinder 2. gram required for the operation concerned. Said connection may instead be put in communication rfhis invention relates topa pressurefluid (pneumatic (LH. position of the slide valve) with the chamber or preferably hydraulic) actuated servo-control device of cylinder 2. l which is suited to uliil'theA requirements as set forth Connection i4 is permanently in communication with above and nonetheless has a high constructional and opthe L. H. chamber of cylinder 2 and, through the openerational simplicity which imparts thereto exceptional ing i7 oi pipe 15, with the port 13. Further, when the qualities of economy, long life and reliability of operaslide valve is displaced to the right, said connection will tion. This device is particularly useful for engagement also be put in communication with a port 19 provided control of the clutch of a motor vehicle, and will be in the wall of cylinder 2, displaced on the right relative described below with reference to this typical application; 40 to port i5. it is understood, however, that said device may be used Connection i5 is in communication, through aduct 20 1for many other applications, either in vehicles, or in liftshown in broken lines, with a port 21 provided in the ing apparatus, or in machine tools and generally in sevwall of cylinder 2, displaced on the left relative to port eral and various lieldsof engineering. i8. Further, when the slide valve is displaced to the The device in 'accordance with this invention is based 4,5 right, said connection will also'be in communication with on the principle of performing `the operation required the H. chamber of cylinder 2. through a pipe 22. by means ot a piston slidably mounted within a'cylinder, When the device is at rest, it has the configuration whose feeding is controlled-by a slide valve and whose shown in EEG. i. The drive member of slide valve 9 will walis are provided with ports which are covered by the maintain the latter to the right: piston l. is at the end piston during a portion of its stroke and whose connecof its stroke at the right and is held there by a return tions with the pressureluid circuit are at least in part member, such as a spring, for the purpose of illustration controlled by said slide valve, said ports producing the diagrammaticaily shown at 3d, but generally forming part esired variation in the displacement speed of the piston of the member to ce operated, as in particular in the case when the latter coversor respectively ceases to cover r of a clutch; this, in the example, is now engaged and in hem. The various programs which can becarried out 50 conditions of normal operation. In this configuration,

depend on the positionofsaid ports and on the dimenpump P delivers fluid under pressure to connection 13, sionsv4 of the device, soy that the latter mustpvaryv in size whencethrough pipe i6, 17-the fluid reaches the conand shape depending onthe requirements of any particnection ld and then flows back to pump P, without exertular application. l ing any action. Communication of pipe 16 with connec- The following description refers to a nonlimiting em- 50 tion i3 may be omitted in those instances when it is not bodiment, give by way of example, which is particularly ece'ssary to maintain the circulation of iiuid mentioned suited to, the typical application mentioned above, and above, eg. if the circuit ofthe device is branched oifro'm is shown inthe accompanying drawings, wherein: the pressure lubrication circuit of the engine.y

FlGS. l to `6 show the device according to the inven- When the clutch must be disengaged, the drive member tion, in a simple form thereof, illustrated in a somewhat cifthesiide valve 9 (for instance anelectromagnet) will diagrarnrnaticaly longitudinal section and in various` posii displace said slide valve to the left, thereby puttingithe tions or" operation; Y connection i3 in communication with the R. H. chamber FIG. 7 shows, separately, a Vcomplementary device of cylinder 2, so that the iluid under pressure will displace which can be added to the object of the invention in piston l (FGURE 2) with its rod e and the driven order to improve the perfomance thereof, and 79 member to the let while the fluid escapes from the L. H. FiG. 8 repeats the diagram OFIG. 5, completed with chamber of the cylinder directly through the connection the device shown in FIG. 7. id. The piston is displaced to the lett up to the end'of es its stroke, and in this position (FIGURE 3) it will expose port it, thereby permitting the fluid-coming from connection 13to reach the discharge connection lll through opening 17. The device remains in this position (clutch disengaged) until the drive member of slide valve 9 will again displace the latter towards the right. Being then driven by its return member, due to lack of iiuid pressure in the R. H. chamber of cylinder 2, the piston ll will bev displaced in the return stroke (FIGURE 4) at high speed because the iluid escapes from the R. H. chamber of cylinder 2 through port l@ and connection llt with a slight resistance. When, however, in its movement piston ll will cover port 19 (FlGURE 5), the fluid may come out from the R. H. chamber of the cylinder only through pipe 22 and connection 15 and then through the ow regulator R, which oters a comparatively high resistance suitably chosen so that the speed of piston il will be limited, as required. To this stage of movement of piston 1 there will correspond the actual engagement of the clutch member, which must take place slowly. Continuing in its slow stroke, piston ll will expose port 2l at a given moment, thereby establishing a communication of low resistance between the two chambers of the cylinder along the pipe 22, 2li, 2li, so that the piston will again be accelerated and covers the last portion of its stroke at high speed (FIGURE 6), finally again reaching the position of rest.

The extent of the various portions of the stroke may bevdetermined by regulating the position of ports 19 and 2l, whilst the speed of the various movement stages will depend on the resistanceand therefore on the inner diameterof the various pipes and the regulator R, as weil as on the force of the return member; all these factors may be determined at will.

in some applications, such as the engagement of a clutch, the performance of the device described-already satisfactory per se could be further improved if the reduced displacement speed of the engagement control member, in the middle stage of said engagement, were not a constant and invariable one but would depend on the Y actual working conditions of the engine when engagement is made; more particularly, it would be advantageous to eiiect the engagement more slowly during the starting stage of the vehicle and more rapidly upon shifting gears when said vehicle is already in movement. These various stages substantially differ in that at starting the engine is caused to run at a comparatively low speed, whereas on shifting gears during normal running the speed of the engine is considerably higher. Therefore, the objects of the instant invention also comprise a complementary device which may be applied to or embodied in the device described above, so as to modify the sliding speed of piston il during its middle stage of movement depending on the speed of revolution of the engine or, where preferred, on another factor suitably chosen, or also with manual control.

r:This complementary device comprises a body 26 which is bored at the inside so as to form a little cylinder wherein can freely slide a plunger 27 in which a helical spring 23 is seated; this spring abuts against a threaded plug 29 screwed in a metal ring :ttl which closes'the one end of the little cylinder, while the opposite end of the latter is closed by a pipe connection 31 integral with a pipe .f2 and extending into the inside of said litle cylinder with a flange 33 which limits the stroke of plunger 27 and is provided with holes in its side walls;.the plunger Z7 is urged by the spring 28 against ange 33, in an inoperative position, and the load 'of said spring may be adjusted by means of the threaded plug Z9.

The walls of the body 26 are provided with two ports 24 and 25, the rst of which is adjacent to pipe connection 31 and is permanently in communication with the pipe 32 through the holes in flange 33, whilst the second of said ports is obstructed by plunger 27 in the inoperative position of FIG. 7.v ln another point of the Wall of bodyk 26, and in the same diametral plane of port 25, another opening d is provided, which communicates with a pipe connection The outer surface of plunger 27 is formed with an annular groove 36, in a position such as to register with ports 25 and 3-4 and to connect them together when plunger Z7, overcoming the force of spring 2S, is displaced to the right until it will abut against the metal ring 30. A further annular groove 37, provided in the outer surtace of plunger 27 and communicating with the inner recess ot the latter which contains the spring 28, permits passage ol: iluid between plunger Z7 and the cylinder during the movement ot said plunger.

The body 26 of this complementary device is intended to be mounted on the casing 3 and the head 5 of the device described above, with port 24 communicating with connection id oi head 5 and with port 25 in register with connection l5 of casing 3. On the connection 13 of head t there is fastened the pipe 23 leading to the arrival of the pressure fluid from the circulating pump, whilst the lines leading to pipe connections 31 and 35 are connected with the fluid reservoir for intake of said circulating pump.

The face of plunger 27, opposite to llange 33, is acted upon by a tiuid pressure which corresponds t-o the pressure drop along pipe 32, of comparatively reduced inner diameter as compared to that of pipe 14, and is a function of the delivery of said circulating pump and therefore generally of the speed of the engine lby which the pump is driven. The load of spring 28 is adjusted in such a manner that, when the engine is running at low speed, said pressure will be overcome by said spring, which maintains plunger 27 in its inoperative position, as shown in FlG. 7. lln this position, communication between connection and pipe connection 35 is established only by the restricted passage (clearance) 'between the outer sufface of plunger 27 and the little cylinder bored in body 26, and therefore it will oder a considerable resistance thereby causing a considerable slowing down of the movement et piston 1 during the middle stage of its displacement of engagement. The clearance between plunger 27 and the little cylinder is therefore chosen, or integrated with connecting grooves of small cross section, so that the engagement speed in these conditions will be suited for starting of the vehicle.

When, instead, the speed of the engine is somewhat higher, as for instance during gear shifting, the pressure acting upon the face of plunger 27 opposite to ilange 33 is in excess of the adjustment or" spring 28, whereby said plunger`27 will be displaced in the operative position as shown in FIG. 8. Communication between connection l5 and pipe connection 35 is then established by the annular groove 3d of comparatively large cross section and therefore entering a reduced resistance; it follows that, in these conditions, engagement will take place more rapidly. The cross section of groove 36 will be chosen, in turn, so that this engagement speed will be adequate.

In the shown embodiment and with the connections described, the 4auxiliary device is suited to regulate or adjust the engagement speed of the main device in a manner automatically dependent on the speed of the engine. lt is apparent, however, that the same devicemerely if differently connected-could receive on the face of plunger 27, opposite to ange 33, a pressure which can be made dependent on any other factor suit-ably chosen to control the engagement speed. On the other hand, the pressure could also lbe applied on said face of the plunger through a band control in case it is preferred to control manually, instead of automatically, the variation of engagement speed. f

it is apparent that the constructional arrangements of the device according to the invention may vary within wide limits without departing from the scope of the `appended claims. For instance, the slide valve may be Iarranged in a manner different from that shown in the drawings, relative to the cylinder; or use may be made of a rotary distributing valve instead of a slide valve.

dicessi The number'of ports provided in the walls of the cylinder may vary, as well as the connection thereof, in case that more than three stages of movement with dilierent speeds are desired or, at contrary, only two stages are required. Correspondingly, the arrangement of the connections in said device Imay vary; further, the connection may even be omitted when the iiow regulator member is disposed iat the inside of the device intself. This is particularly advantageous in the case when said member consists of -a simple diaphragm with gauged hole. The control member of slide valve 9 may -be ofy various types, but preferably it will be electromagnetic .and controlled by means of a push-button disposed on the gear shift lever of the veh-iclewhen the device is applied to motor cars, which is considered to 'be a particularly suitable application. communication between the ports 2S and 34 may be established by means of a groove annular or of different shape, formed in the body 26 of the device, whilst the annular groove 36 in plunger 27 may be replaced with a helical or diiierently shaped groove in order to attain .a more gradual variation or" lthe hydraulic resistance offered to the flow between ports and 34. l Having thus described my invention, what l claim is: l. A pressure fluid actuated servo-control device, comprising a cylinder, a piston reciproc-able within lsaid cylinder, and defining in said cylinder a first chamber and a second vchamber separated from said yfirst chamber, a connection for arrival of a pressure iiuid iiow actuating said reciprocable piston, a pipe connecting said arrival connection with said first chamber of the cylinder, a connection for discharge of the pressure fluid, a pipe connecting said discharge connection with said second ch-amber of the cy-linder,iports bored in the wall of said cylinder, pipes connecting said ports with said discharge connection, means inserted in one of said pipes for re. straining the fluid flowv therein, Iand a slide valve inserted in said pipes, whereby said slide valve controls the fluid flow actuating `the forward and rearward movements of said piston reciprocable -in saidcylinder, whilst the rearward movement of said piston takes placerwith a different speed laccording to the position of the piston With respect to said ports bored in the wall of the cylinder.

2. A pressure fluid actuated' servo-control device, comprising a cylinder, a piston reciprocable within said cyl# inder, and defining in said cylinder av first chamber having an end wall and second chamber separated from said first chamber, a connection for arrival of pressure liuid ow, a pipe connecting said arrival connection with said first chamber of the cylinder, a connection for discharge of the pressure tluid, a pipe connecting said discharge connection with saidsecond chamber of the cylinder, a first port bored'in the wall of said cylinder in proximity of the end wall of said first chamber, means for restraining the fluid flow, a pipe connecting said first port with said discharge connection through said means for restraining the fluid flow, a second port boredin the middle portion of the wall of said cylindena pipe connecting said second port with said discharge connection, and a slide valve inserted in 'said pipes for controlling the fluid flow a" tuating theforwardV and rearward movements ofsaid piston reciprocable in said cylinder, whereby the rearward movement of said piston takes place witha high speed as long as said second port is not covered by said piston, and proceeds with a lower speed after said second port has been covered by the piston.

V3. A pressure fluid actuated servo-control device, comprising a cylinder, a piston reciprocable withinr said cylinder, and defining in said cylinder a rst chamber having an end wall and a second chamber separated from said first chamber, a connection for arrival of apressure fluid flow, a pipe connecting said arrival connection with saidfirst chamber of the cylinder, a connection for discharge of the pressure fluid', a pipe connecting said discharge connection with said second chamber of the cylinder, a first port In the auxiliary device, permanent` bored in the wall of said cylinder in proximity of the end wall of said first chamber, means for restraining the fluid dow, a pipe connecting said first port with said discharge connection through said means for restraining the fluid flow, a second port bored in the middle portion of the wall of said cylinder, a pipe directly connecting said first port with said second port, and a slide valve inserted in said pipes for controlling the fluid fiow actuating the forward and rearward movements of said piston reciprocable in said cylinder, whereby the rearward movement of said pston takes place with a reduced speed as long as said second port is covered by said piston, and proceeds with a higher speed after said second port has ceased to be covered by the piston.

4. A pressure fluid actuated servo-control device, cornprising a cyiinder, a piston reciprocable within said cylinder, and defining in said cylinder a first chamber having an end wall and a second chamber separated from said first chamber, a connection for arrival of a pressure fluid iiow, a pipe connecting said arrival connection with said first chamber of the cylinder, a connection for discharge of the pressure fluid, a pipe connecting said discharge connection with said second chamber of the cylinder, a iirst port bored in the wall of said cylinder in proximity of the end wall of said first chamber, means for restraining the fluid flow, a pipe connecting said first port with said discharge connection through said means for restraining the iiuid flow, a second port bored in the middle portion of the wall of said cylinder, a pipe connecting said second port with said discharge connection, a third port bored in the middle portion of the wall of said cylinder7 a pipe directly connecting said iirst port with said third port, and a slide valve inserted in said pipes for controlling the iiuid flow actuating the forward and rearward movements oi said piston reciprocable in said cylinder, whereby the rearward stroke of said piston takes place with a high speed in a first portion of the stroke, as long as said second port is not covered by said piston, proceeds with a lower speed in a second portion of the stroke, after said second port has been covered by the piston while said third port is also covered by the piston, and proceeds further with a high speed in the last portion of the stroke, after said third port has ceased to be covered by the piston.

5. A pressure fluid actuated servo-control device as set forth in claim l, wherein said means for restraining the fluid flow comprises alittle cylinder, a plunger reciprocable within said little cylinder and defining in saidV little cylinder a first little chamber and a second little chamber separated from said first little chamber, said second little chamber being in communication with said discharge connection, a spring abutting against said plunger for forcing it into said second little chamber, a discharge pipe departing from said second little chamber, a discharge port bored in the wall of said first little chamber,

a pipe connecting said first little chamber with the ports with the'outlet of said pipe inthe first little chamber, when said plunger is within the first little chamber, whilst said discharge port and said outlet are connected with a higher resistance when said plunger is within the second little chamber, whereby when the fiuid pressure in said second little chamber exerts on the plunger a lower force than said spring, said plunger is forced into said second chamber and the discharge of the pressure fluid takes place with a high resistance, whilst said discharge takes place with a lower resistance when, said pressure overcoming the force of the spring, said plunger is forced into said first little chamber.

6. A pressure fluid actuated servo-control device as set forth in claim 1, wherein said means for restraining the iiuid fiow comprises a little cylinder, a plunger reciprocable within said little cylinder and defining in said little cylinder ya first little chamber and asecond little chamber separated from said first little chamber, said second little chamber being in communication with said discharge connection, a spring abutting against said plunger within said rst little chamber, a screw-threaded plug constituting the end wall of said rst little chamber, said spring abutting against said plug, a discharge pipe departing from said second little chamber, a discharge port bored in the Wall of said rst little chamber, a pipe connecting said rst little chamber with the ports bored in the Wall of the cyl- Vinder of the servo-control device, and a groove provided on the surface of said plunger and connecting said discharge port with the outlet of said pipe when the plunger is within said first chamber, whereby said spring urges said plunger into said second chamber with a force which may be adjusted by screwing or unscrewing said screw-threaded plug.

References Cited in the le of this patent UNITED STATES PATENTS 530,341 Hill Dec. 4, 1894 f 840,877 Steedman Jan. 8, 1907 10 2,164,865 Keiper July 4, 1939 2,225,315 McCollum Dec. 17, 1940 

1. A PRESSURE FLUID ACTUATED SERVO-CONTROL DEVICE, COMPRISING A CYLINDER, A PISTONRECIPROCABLE WITHIN SAID CYLINDER, AND DEFINING IN SAID CYLINDER A FIRST CHAMBER AND A SECOND CHAMBER SEPARATED FROM SAID FIRST CHAMBER, A CONNECTION FOR ARRIVAL OF A PRESSURE FLUID FLOW ACTUATING SAID RECIPROCABLE PISTON, A PIPE CONNECTING SAID ARRIVAL CONNECTION WITH SAID FIRST CHAMBER OF THE CYLINDER, A CONNECTION FOR DISCHARGE OF THE PRESSURE FLUID, A PIPE CONNECTING SAID DISCHARGE CONNECTION WITH SAID SECOND CHAMBER OF THE CYLINDER, PORTS BORED IN THE WALL OF SAID CYLINDER, PIPES CONNECTING SAID PORTS WITH SAID DISCHARGE CONNECTION, MEANS INSERTED IN ONE OF SAID PIPES FOR RESTRAINING THE FLUID FLOW THEREIN, AND A SLIDE VALVE INSERTED IN SAID PIPES, WHEREBY SAID SLIDE VALVE CONTROLS THE FLUID FLOW ACTUATING THE FORWARD AND REARWARD MOVEMENTS OF SAID PISTON RECIPROCABLE IN SAID CYLINDER, WHILST THE REARWARD MOVEMENT OF SAID PISTON TAKES PLACE WITH A DIFFERENT SPEED ACCORDING TO THE POSITION OF THE PISTON WITH RESPECT TO SAID PORTS BORED IN THE WALL OF THE CYLINDER. 